Aircraft having extensible landing gear positionable for horizontal and vertical take-off



fiwt W49. c. H. ZIMMERMAN ,379

AIRCRAFT HAVING EXTENSIBLE LANDING GEAR POSITIONABLE FOR HORIZONTAL AND VERTICAL TAKE-OFF Filed July 26, 1945 8 Sheets-Sheet 1 IN VEN TOR.

@lmrler H. Zimmerinum ATT'O R N EY w & c. H. ZIMMERMAN ,43 ,379

AIRCRAFT HAVING EXTENSIBLE LANDING GEAR POSITIONABLE FOR HORIZONTAL AND VERTICAL TAKE-OFF Filed July 26, 1945 8 Sheets-Sheet 2 INVENTOR.

@harles H. Zimmerman ATTORNEY W H9. c, zlMMERMAN 2,41,339

AIRCRAFT HAVING EXTENSIBLE LANDING GEAR POSITIONABLE FOR HORIZONTAL AND VERTICAL TAKE-OFF Filed July 26, 1945 8 Sheets-Sheet 5 .INVENTOR.

Maurie; H Zimmerman 1/1 UAW/m.

ATTO RN EY C. H. ZIMMERMAN AIRCRAFT HAVING EXTENSIBLE LANDING GEAR POSITIONABLE FOR HORIZONTAL AND VERTICAL TAKE-OFF 8 Sheets-Sheet Filed July 26, 1945 was INVENTOR.

Charles H. Zimmerman ATTORNEY wt 8 149.. c. H. ZIMMERMAN 2,481,379

AIRCRAFT HAVING EXTENSIBLE LANDING GEAR POSITIONABLE FOR HORIZONTAL AND VERTICAL TAKE-OFF Filed July 26, 1945 8 Sheets-Sheet 5 I N V EN TOR.

Marie; H. Zl'm merman ATTORNEY Swpt fi, W49. c. H. ZIMMERMAN 2,433,379

AIRCRAFT HAVING EXTENSIBLE LANDING GEAR POSITIONABLE FOR HORIZONTAL AND. VERTICAL TAKE-OFF Filed July 26, 1945 8 Sheets-Sheet 6 JNVENTOR.

Char/es H. Zimmeqman ATTORNEY c. H. ZIMMERMAN 2,481,379 IRCRAFT HAVING EXTENSIBLE LANDING GEAR POSITIONABLE FOR HORIZONTAL AND VERTICAL TAKE-CFF 8 Sheets-Sheet 7 Filed July 26, 1945 INVENTOR.

@harles H. Zimmerman W3. WW

ATTORNEY apt 194%.. c. H. ZIMMERMAN 9 L AIRCRAFT HAVING EXTENSIBLE' LANDING GEAR POSITIONABLE FOR HORIZONTAL AND VERTICAL TAKE-OFF 8 Sheets-Sheet 8 Filed July 26, 1945 INVENTOR.

Charles H. Zimmerman BY AT TOR MEX Patented Sept. 6,1949

AIRCRAFT HAVING EXTENSIBLE LANDING GEAR POSITIONABLE FOR HORIZONTAL AND VERTICAL TAKE-OFF Charles H. Zimmerman, Nichols, Conn.

Application July 26, 1945, Serial No. 607,168

16 Claims.

This invention relates to low aspect ratio, allwing aircraft of the type disclosed in my U. S. Patent No. 2,108,093 and has for one of its objects to increase the utility of such aircraft by providing a mechanism which will fully realize those characteristics of a low aspect ratio, all-wing aircraft which permit landing and take-off without ground run.

More specifically, it is an object of this invention to provide a novel multi-position landing gear and trailing edge flap combination for use on low aspect ratio, all-wing aircraft.

Another object of the invention is to provide such a landing gear, trailing-edge-fiap combination as will allow a low aspect ratio, all-wing aircraft to possess all the advantages of a hellcopter.

A still further object of the invention is to provide not only for take-off and landing of an aircraft of this general type without ground run, but also to provide for retaining in such aircraft the ability for take-off and landing with ground run in conventional airplane fashion when excessive loading or impaired power makes such a procedure desirable.

A still more specific object of the invention is to provide a landing gear for use in all-wing aircraft for conventional airplane take-off and landing which may be telescopically extended for take-01f or landing helicopter fashion and which may be fully retracted while the craft is in flight, and to provide a trailing edge flap which will enable the aircraft to be held in longitudinal trim regardless of its distance from the ground.

A further object is generally to improve the construction and performance of all-wing aircraft.

These and other objects and advantages of the invention will be apparent from the drawings and from the following description.

In the accompanying drawings, wherein like reference numerals designate similar parts throughout, there is illustrated a suitable mechanical embodiment for the purpose of disclosing the invention. The drawings, however, are for the purpose of illustration only and are not to be construed as limiting or restricting the invention, since it will be apparent to those skilled in the art that many changes in the detailed design of the illustrated embodiment may be resorted to without exceeding the scope of the invention as defined in the claims appended hereto.

In the drawings,

Fig. 1 is a rear perspective view of an aircraft embodying the invention;

in phantom, the landing gear being shown in full lines in position for airplane take-off;

Fig. 4 is a phantom side elevation of the aircraft with the landing gear shown fully retracted as in flight;

Fig. 5 is a phantom side elevation of the aircraft with the landing gear shown in position for helicopter take-off;

Fig. 6 is a phantom side elevation of the aircraft with the landing gear shown in position for airplane take-off;

Fig. '7 is a section taken on line l--'| of Fig. 6 showing mechanism controlled by certain movements of the landing gear for connecting the trailing edge flap to the pilot operated control column; 1

Fig. 8 is a plan view of the mechanism shown in Fig. '7

Fig. 9 is a view of the landing gear actuating device looking aft as the device is installed in the aircraft;

Fig. 10 is a view of the actuating device looking inboard in the airplane;

Fig. 11 is a view of the upper extremity of the landing gear looking aft as the device would be installed in the airplane;

Fig. 12 is a view of the mechanism of Fig. 11 looking inboard in the airplane;

Fig. 13 is a section taken on line l3-I3 of the Fig. 12; v

Fig. 14 is a section taken on line l4-l4 of Fig. 11;

Fig. 15 is a fragmentary plan View of Fig. 9 showing the indicator;

Fig. 16 is a sectional detail through the clutch of Fig. '7

Fig. 1'? is a diagrammatic showing of one of the control mechanisms for the landing gear;

Fig. 18 is a diagrammatic perspective View of the mechanism of Figs. 7 and 8; and

Fig. 19 is a detailed view of an oleo strut.

Fig. 1 illustrates generally the type of aircraft in which the invention is preferably embodied. Numeral Ill indicates the craft as a whole which has a streamlined body I I comprising the fuselage and wing structure which encloses and supports the passengers and the power plant as well as any other load. The craft has one or more propellers so disposed and of sufiicient diameter so that substantially all of the aircraft lies within the propeller slipstream. In the preferred embodiment the aircraft is provided with two propellers l3 and I4 slightly forward of the leading edge of the wing adjacent the lateral extremities thereof geared together to turn in opposite directions and at the same speed. The propellers are of the controllable pitch type having constant speed governors associated therewith. The power plant may consist of. oneor more engines but must provide suificientpower to enablethe propellers to produce a static thrust in excess of the weight of the aircraft. The craft preferably has laterally extending rearwardly disposed unit horizontal tail surfaces l5 and |6.-and.t-w0;vertical:tail surfaces I 1 and I8 which aredisposed at the trailing edge of the body H and at the lateral extremities of a trailing edge flap [.9 pivotedtothe aircraft body at I911, which is part of the invention and will be more fully described hereinafter. Herein the vertical surfaces I1 and H! are mounted in fixed relation to the movable flap I9 so as to move therewith as the latter moves about its pivot Isa. In general the craft may be termed a low aspect ratio, flying wing helicopter having prone positioned pilot and-passenger installation.

Numeral 2|] in Fig.2 indicates generally the forward landinggear of the aircraft. The oleo struts are conventional self-contained shock absorbing units telescopically slidable within cylindrical casings 2| and 22. The oleo units are indicated at 23 and 24 in Fig. -2 in their fully extended positions. The oleos '23, 24 carry piston heads on their upper ends, one of which is shown at 24a in 'Figs. 13 and 14, which open at their upper ends into the casings 2|, 22. The telescoping oleo struts 23, 24 and the casings 2|, 22 of the landing gear differ 'from the usual landing gear, however, in that the oleos are adapted to occupy either of two positions relative to the casings in either of which the oleo struts cushion the landing of the craft in different flight attitudes of the latter, as will hereinafter be explained. Gear has fixed length drag links '25 and 26, a rigid transverse'brace 21 and diagonal cable type braces'28 and 29. Wheels '30 and 3| aremounted at the lower extremities of the oleos 23 and 24 in a conventional manner. Fixed tail wheels 32 and 33 are provided adj acent-the latera1 extremities of the trailing edge portion of body independent of landing gear '20.

As shown in Fig. 3 the upper ends of casings 2| and 22 are mounted at ;34 and 35 at the forward ends of channel-type tracks 36 and 31 which are disposed generally longitudinally in the aircraft, but are inclinedforwardly and downwardly with respect to the longitudinal axis of the aircraft and are fixedly mountedon the structure thereof. As further shown in Fig. 3, the system includes landing gear operating mechanism .38 and a linkage more fully describedhereinafter, generally indicated at 39, for interconnecting the operating mechanism for the trailing edge flap l9, whenever the gear is in its most extended position, with a pilot operated control column 40 for operating the tail surfaces l5 and I6.

Cables 4| and 42 are provided'for extending and retracting the gear, cable 4| having one end fixed at 43 to the base of oleo 23 and cable 42 having one end similarly fixed at 44 to oleo 24. Cable 4| is disposed to run through pulleys 4'5, 46 and 49 and cable .42 through pulleys 41 and 48, both cables having their ends fixed to cable drum 54 of mechanism .38 in such manner that they are wound and unwound in unison by opposite rotations of the drum. Control column 40 is connected to the horizontal tail surf ace control shaft 50 by link 5| which is pivotally mounted on con trol column 40 at 52 and at its opposite end is pivotally connected to arm 53 which depends from shaft 58, by which linkage the tail surfaces l5 and I6 are at all times controllable by the pilot from column 40.

The landing gear operating mechanism is best shown in Figs. 9, 10 and 1 5 and consists of a cable drum ratchet mechanism. Cable drum 54 is mounted on shaft 55 in a freely rotatable manner and has mounted concentrically with it and fixed to it ratchet plate 56. Also mounted for free rotation on shaft'55 isa rod 51 the upper end of which carrieshandle grip 58. Rod 51 and cable drum 54 are retained in fixed relationship on shaft 5 5.by spacers 59, and 6| and support members 62 and 63. Push rod 64 is mounted immediately adjacent and longitudinally parallel to rod 5.1, being constrained from any but longitudinal motion by guide 65 fixed to rod 51. Push rod 64 is spring biased in an upward direction by compression spring 66 mounted concentrically therewith and acting at its opposite ends against guide 65 and terminal cap 61 of rod 64. Pawl 68 is pivotally attached to the lower extremity of push rod 64 at right angles thereto and is also pivotally mounted on the lower end of rod 64 at 69. In its normal position the free extremity 18 of pawl 68 is engaged by some tooth of ratchet 56. Supported on structure adjacent to ratchet 56 is a second pawl 1| normally biased by spring 12 into engagement with the teeth of ratchet 56. Indicator 13 shown in plan view in Fig. 15 is mounted in any convenient manner to be actuated by operating mechanism '38 so as to indicate the position of the landing gear as being either in up, airplane 0rhe1icopter position.

It will be apparent from the above that to wind cables 4| and 42 onto the cable drum it is only necessary to pull handle 58 in'the direction of the full line arrow in Fig. 10, that is, aft in the airplane, thus imparting motion from the pawl 68 to the ratchet 56. This can be done in any convenient number of reciprocations of the handle 53 for it will be seen that pawl 1| will constrain the drum from releasing the cable. To release the cable drum, cap 61 of push rod 64 is depressed against the action of spring 65, thus causing the pawl 68 to rotate about point 59 thereby disengaging its extremity 10 from the teeth of ratchet 55. The handle 58 is then pushed in the direction of the dotted line arrow, i. e. forward in the airplane until the lowermost portion of push rod 64 engages tripping arm 14 of holding pawl 1| and causes it to rotate about its pivot 15 against the bias of spring 12. This movement of operating mechanism 38 through approximately 45 disengages pawl 1| from the teeth of ratchet plate 56 and leaves the drum free to rotate, thereby releasing cables 4| and 42.

As previously mentioned the uppermost extremities of casings 2| and 22 are mounted for sliding movement along sets of tracks 36 and 31 respectively, the upper ends of these casings bein located at the forward ends of these tracks at points 34 and 35 in the position of the parts shown in Fig. 3. Since the mountings at these points are identical only one will be described in reference to Figs. 11, 12 and 14 wherein this mounting mechanism is best illustrated in connection with casing 22.

A cap 86 is fixedly attached to the upper portion of casin 22. In plan view cap is generally annular except for a furcated portion 8| which protrudes from one side thereof and between the furcations of which pulley 4-1 is mounted on bolt 82. At its topmost extremity the cap 80 has a forwardly directed hook portion 84 which extends horizontally across it and which is disposed in such manner as to partially encircle a stop pin 85 which is fixed to aircraft structure adjacent and slightly above the forward end of track 31. At 90 to furcated portion BI cap 80 has protruding from opposite sides thereof a stud 86 which carries at each of its ends a roller 91 positioned within one of the two confronting channel members which comprise the track 31, as shown most clearly in Fig. 13. As indicated at 133 cap 30 has an angular slot cut below and at right angles to hook 84 to permit cable 42 to pass therethrough without interference. Casing cap is provided with a longitudinally drilled two-diameter hole 95 which contains a plunger 90 slidably mounted therein having an upper portion 91 of larger diameter than its lower portion 90. Plunger 96 is constantly biased upward by compression spring 99 acting at one end against the shoulder in hole 95 and at its other end against the lower extremity of portion 91. The lower end of plunger 96 is pivotally connected to the free end of lever I00 fulcrumed at IOI on the lower extremity of a depending support I02 which has its upper extremity fixed to casing cap 80. The free end of lever I 00 is normally held by spring 99 in a slot I03 cut in the piston head wall 92 and is withdrawn from this slot only when plunger 95 is depressed.

A latch I04 is pivotally mounted at I05 on adjacent aircraft structure, this latch being limited in its downward motion when it is free by stop I00 and being biased constantly downward into latching engagement with hook portion 84 when the latter is abutting stop pin 85 by two strong springs I01 and I08 (Fig. 11) which have their upper ends fixed to latch I04 and their lower ends anchored to fixed aircraft structure at I09 and H0.

Mechanism is provided by which the latch I04 is released upon full retraction of the oleo struts into casings 2I and 22 by winding up cables 4| and 42 on the drum 54. This mechanism, as shown in Figs. 12 and 14, includes an abutment 89 fixed to cable 42 and a lever 90 pivoted at 82 and having an angular extremity 9I engageable by abutment 89 to move the lever 90 clockwise about its pivot 82 when the upper end of piston head 24a reaches the upper end of casing 22. Clockwise movement of lever 90 causes the upper end of the latter to engage a depending finger on a latch actuator 92 pivoted at I05 to rotate the actuator counterclockwise. This results in the release of latch I04 by the engagement therewith of an upstanding finger on actuator 92. In Figs. 12 and 14 the abutment 89 is about to efiect the release of latch I04.

If the pilot wishes to extend his landing gear when in flight from the retracted position in which the rollers 81 are disposed in the extreme right-hand end of channel track 31, shown in Fig. 4, to the position shown in Fig. 6 for airplane landing with ground run, in which the rollers are disposed at the extreme left-hand end of the channel track, he merely'depresses cap 61 on push rod 64 and pushes handle 58 forward 45. As previously described, this motion of the handle releases both pawls from the ratchet wheel on drum 54 and allows cables 4| and 44 to run out freely under the weight of the landing gear. As the cable runs out, rollers 81 carrying the casings 2I and 22 with them move forward on the downwardly inclined track 31, motion being constrained by fixed length drag link 25 whichro- 6 tates about a fixed horizontal axis within the fuselage, the axis about which link 26 rotates being the shaft III (Fig. 6) which is journaled on a fixed part of the airplane structure. As casing cap 80 reaches the forwardmost and lowest portion of track 31, hook portion 84 encircles stop pin 85 and is held by gravity against this stop. Also latch I04 engages and depresses plunger 96 to unlock the oleo 24. Oleo 24 is thus permitted to extend slightly. As the indicator needle II2 on actuator indicator I13 reads airplane the pilot removes his hand from actuator handle 58 and the cable controlling the descent of the oleo 24 is locked in place at the proper point. In airplane position the oleo strut 24 has extended itself from the cylinder 22 Only enough to enable the oleo strut to give proper shock absorbing qualities upon landing and to provide in the event of extreme shock in landing for engagement of the upper end of the piston wall 92 on the upper end of the oleo strut with a resilient member in the upper end of the casing 22, herein a sponge rubber pad. The landing gear 20 is locked in place by latch I04 and the craft is prepared to make a landing in conventional fashion as an airplane.

To retract the landing gear after having made a take-off as a conventional airplane the pilot pulls handle 50 on operating mechanism 38 toward him. This motion rotates cable drum 54 clockwise as viewed in Fig. 10 by the driving action of pawl 10 and the holding action of pawl 1 I, thus retracting the oleo 24 into casing 22. As the oleo becomes fully retracted in the casing, abutment 89 engages lever 90 causing latch I 04 to be released. The pilot continues to pull handle 58 on operating mechanism 38 toward him in pump-like fashion thus further retracting cables 4| and 42 and causing rollers 31 carrying the landing gear to move aft along track 31 until the hand II2 on indicator 13 reads up in which position the pilot removes his hand from handle 58, thus locking the cable and hence the gear in fully retracted position.

As soon as casing cap has moved up the track 31 sufficiently to move plunger 96 out from under latch I04, this plunger moves upward under the bias of its spring 99, thus rotating lever I00 counterclockwise about point IOI' and allowing the free end of lever I00 to pass into slot I03 in piston head wall 92, thus locking the 6E0 24 at a time when it must be in fully retracted position. Means which will be described below are also provided for slackening cable braces 28 and 29 upon retraction of the landing gear so these cables will rest just inside the bottom contour of the craft in slots provided for the purpose, as best indicated in Fig. 4.

Experimentation with the type of craft to which the invention is applied has proved that when the craft is very near the ground in true hovering attitude there is encountered at the trailing edge thereof a cushioning effect of the air which manifests itself as an undesirable pitching moment or nose-over tendency.

To overcome this condition and permit successful landing and take-off from the true hovering attitude (Figs. 2 and 5) the trailing edge fiap I9 and means for controlling said flap are provided. It was found that although this fiap could be used for other purposes while in flight, such as for additional longitudinal stability, its important and most useful function is to overcome the pitching moment encountered near the ground at low speeds. In accordance with this invention the flap-I9 is freely movableabout its pivot 19a and means are provided to control the pivotal movements of the flap from the main control column 40 simultaneously with the horizontal tail surfaces I and 16 but only at such time as the landing gear is in fully extended position as it wouldnaturally be when the craft is near the groundin true hovering attitude. When the flap is not engaged by the-control mechanism for surfaces :I 5 and I6 its .position is satisfactorily determined by interaction of gravity and airload moments.

The control mechanism for flap I9 is best shown in Figs. 3, 6, '7, 8, and 18. As previously described control shaft 50 for operating surfaces {I5 and 4:6 is rotated from the control column 40 throughthe rigid connection of shaft 50 to arm 53 which is in turn connected by link 5| to'the control column (Fig. 3). A clutch member H5 of generally cylindrical shape is concentrically mounted on .shaft 50 and is fixedly pinned thereto and hasa-n annular clutch face concentric with shaft 50. Also mounted to rotate about shaft 55 is asecond clutch'member I I6 having a cooperating face adapted to .cooperate with clutch face of member H5 and normally spaced from the latter by :a compression spring l'II. Clutch member I I6 is keyed i130 sleeve '1 I18, sleeve .I I8 being concentric with shaft 55.0 .and free to rotate thereabout in bearings I3I and I32. An arm I26 is provided at right angles to sleeve '8 which is pivotally connectedto link I30 .of the operating linkage for flap I9, .and the motion of column 40 is imparted by flap operating linkage [.30 to flap I 9 whenever clutch member H5 and H6 are engaged.

Engagement of clutch members H5 and H6 is controlled by the landing gear in its final extending movement. To this end drag link 26 is pinned to shaft "I II journaled on a fixed part of the airplane. Sh ft III also has a rearwardly directed arm I'22-"nxedly pinned to it and parallel with drag link 26. The free end of arm I22 is universally mounted at 123 to a telescoping member I 24 which is universally mounted at its other end to one end of a clutch actuating lever I25 at I26, the opposite end of lever I25 being disposed to actuate clutch member II6 to the left in Fig. '7 once tha-tlever is pivoted in a counterclockwise direction about its fulcrum I21. As shown in Fig. 16 the free end of lever I25 comprises a yoke which straddles sleeve H8 and carries opposed pins I25a that project inwardly into an annular groove II 8a in the sleeve. Member I24 is constructed with provision for lost motion in the direction of its length and also has suitable abutment means to enable it to act as a simple drag link when telescoping portion I28 thereof is fully extended from portion I 29.

Shaft HI also carries rigidly pinned thereto cam I33 adapted to engage the free end of a lever 1'34 pivoted at I35 to which the end of side brace cable 28 is fixed at I36 (Fig. 8). Cable 28 adjacent its point of attachment to lever I34 at I36 passes over a pulley I38 journaled on rod II I and a second pulley I39 at a suitable angle thereto carried by link 26. The forward portion of lever I34 has a radius to correspond to the motion of cam I33 so that motion of the latter will impart no motion to lever I'34 through one portion of angular movement thereof. As clockwise motion of cam I33 continues however lever I34 is permitted to pivot in a counterclockwise direction about I35 fromthe Fig. 6 position to the Fig. 4 position causing the point of attachment of cable 28 .to move toward pulley I38, thus slackeningside brace cable 28 in the retracted position of the landing gear shown in Fig. 4.

Having described the construction of the mechanism involved it is now possible to describe the operation of preparing the aircraft for helicopter landing in the manner provided by this invention. From .a normal cruising position at, for example, 200 M. P. H., to put the craft into a hovering position the pilot pulls the control column 40 toward him and reduces his throttle setting until his speed is greatly reduced. As the pilot continues to pull the control column .40 toward him horizontal control surfaces I5 and I6 move into the position shown in Fig. 2 and the craft assumes a hovering position, the pitch of the propeller blades being properly adjusted by automatic governors. Once in the hovering a-ttitude the pilot must increase his throttle setting in order not to lose altitude as he moves the control column 40 toward neutral position.

If the pilot at this point desires to extend his landing gear in preparation for a helicopter landing he depresses push rod Bl on actuator mechanism 38-and pushes handle 58 forward in the manner described above for extending the gear to a position for airplane landing. As the plunger 96 on the strut moves under latch I04 the oleo 2-4 is unlocked. The oleo 24 is now free to extend as cable 42 is released.

As cam I33 is rotated it engages lever I34 causing the latter to rotate upward about point thus tightening side brace .cable 28 to its proper taut condition. The pilot continues to hold handle 58 of operating mechanism '38 a quarter turn forward until the needle II2 on indicator I3 shows that the gear is fully extended, oleo 24 having fully extended itself from casing 22 into the position shown in Figs. 2 and 5. To maintain the gear in-helicopter position means including an air compressor are provided for supplying air under pressure to casings 2-I and 22 to make the casings in effect rigid columns during landing operations. Thus when the pilot has released the gear for movement by gravity to the helicopter position and is preparing to make a landing he closes switch I40 (Fig. 1.7), which is located in the cockpit, causing from the compressor I 4| to enter casings .21 and 22 through flexible conduit I42. At this point the pilot releases push rod 6'! and removes his hand from handle 58 thus locking the operating mechanism 58 in the fully extended position of the gear. As the gear is extended from position of airplane landing to helicopter landing, drag link 26 is rotated about point III and, as described above, imparts proportional angular motion both to cam I33 and link I,22. The motion imparted to push-pull rod I24 as the gear descends from fully retracted position to position for airplane landing, portion 128 becoming fully extended from portion I29 of member I24, is as described above, lost motion. As the gear extends from airplane landing position to helicopter position, however, the motion imparted to arm N12 is in turn conveyed to member I24 which, being fully extended, acts as a rigid link and imparts motion to lever I 25 at I26 causing lever I25 to rotate on its fulcrum 'If2'I thus in turn causing clutch member H6 to engage cooperating clutch member I I5 against the bias of spring III. Since clutch member :I I5 'is rigidly fixed to horizontal tail surface control shaft 50, it can be seen that any motion imparted to this control shaft by column 40 will also be imparted to sleeve I I 8 to which .clutch member I'IB is keyed, .and hence via arm I20 depending from sleeve 8 to trailing edge flap control linkage I30. The shape of the jaws on clutch members H5 and '6 is such that, even if the relation between the setting of the horizontal tail surfaces I5 and I6 and the setting of the flap I9 is incorrect prior to their engagement, they will be brought into the correct relative position by the cam action of the jaws during the engaging operation.

Having extended the landing gear and having provided for trim at low speeds near the ground the pilot decreases his power and gently descends in a hovering position toward the ground. As he nears the ground in order to settle thereon the pilot deflects his horizontal tail surfaces and trailing edge flap I9 by actuation of control column 49. This counteracts the cushioning effect of the air which otherwise would cause a nose-over tendency, and the craft is allowed to settle on the ground in the position indicated in Fig. 5,

Since it is a characteristic of the trailing edge flap I9 to offer automatic correction to the tailup tendency encountered near the ground at low speeds, in certain applications it will prove sufficient to have flap I9 merely a spring-loaded, freely-floating surface rather than having it interconnected with the control for the hori-. zontal tail surfaces 15 and I6. In any case flap I9 is provided on its lower surface with a stop or bumper mechanism Ila and I8a as shown in Fig. 1. The bumper mechanism may, as herein shown, comprise merely a continuation of the vertical tail surfaces below the'horizontal surfaces, the extended portions functioning as a stop or ground contact member. In the event the control of flap I9 is not attached to the control linkage of the horizontal tail surfaces, contact of the bumper device with the ground maintains the flap in a fully up position in readiness for the next takeoff. In addition to its basic function of providing for trim in hovering or at very low speeds near the ground the trailing edge flap offers several other advantages in that (a) it allows for a reduction in landing gear length; (b) it may be used as a stabilizing flap in the air; it offers a firm foundation for the aircraft on the ground and prevents any possibility of overturning; and (d) it acts as a fairing for the tail wheel.

It is readily apparent that following take-off in a hovering position the pilot operates switch I48 to energize solenoid valve I44 thus bleeding the air within casings 2| and 22. He then retracts his landing gear by rotating handle 58 of operating mechanism 38 thus retracting oleo 24 into cylinder 22 and placing the gear first in position :for airplane landing and then in the fully retracted position in the manner previously described. It can be seen that as drag link 26 pivots upwardly it imparts motion to cam I33 and arm I22 which act in the reverse manner from that above described thus permitting side brace cables 28 and 29 to slacken and clutch member lit to disengage itself from clutch member H thereby allowing the operating mechanism for tail surfaces I5 and I6 to become free of the trailing edge flap I9.

It will be evident that if the pilot wishes to extend the oleos from the airplane position to the helicopter position when the aircraft is on the ground, this can be done by closing the switch I49 to supply air to the casings 2|, 22. Closing switch MI will bleed the air in the cas- 10 ings 2| 22 and return the oleos to the position shown in Fig. 6.

It will be evident that as a result of this invention mechanism has been provided enabling low aspect ratio, all-wing aircraft to take off and land in pure hovering attitude as a helicopter, while still retaining the ability to take off and land as a conventional airplane when such a procedure is preferred.

It will also be evident that means has been provided for overcoming the nose-over tendency of an all-wing aircraft as it approaches the ground in a helicopter landing.

While a suitable mechanical embodiment of the invention has been hereinabove described and illustrated in the accompanying drawings for the purpose of disclosing the same, it is to be understood that the invention is not limited to the particular arrangement so illustrated and described, but many changes in the arrangement of the various parts may be resorted to, and that the invention may be applied to a variety of aircraft types without exceeding its scope as defined in the claims appended hereto.

Having now described the invention so that others skilled in the art may clearly understand the same, what is desired to secure by Letters Patent is as follows:

1. An aircraft capable of both horizontal and vertical flight including a supporting structure, means for positioning said craft for horizontal take-off including landing gear and a tail support, said landing gear including casings pivotally connected to said structure at their upper ends and struts telescoping into said casings and carrying landing wheels at their free ends, means operable when said casings and struts are telescoped for retracting said landing gear into said supporting structure, means operable when said casings are extended for extending said struts relative to said casings to move said wheels beyond the horizontal take-off position thereof for positioning said craft for vertical take-off, and means for locking said casings against retraction except when said struts are fully retracted into said casings.

2. An aircraft capable of both horizontal and vertical flight including a supporting structure, means for positioning said craft for horizontal take-off including landing gear and a tail support, said landing gear comprising casings pivotally supported on said structure at their upper ends and oleo units telescoping into said casings and carrying landing wheels at their free ends, means for positioning said craft for vertical take-off including means for extending said casings and for extending said oleo units relative to said casings, means controlled by the pilot for first retracting said oleo units and subsequently retracting said casings, means for releasably holding said casings in extended position, and means controlled by said oleo units upon full retraction thereof for releasing said holding means.

3. An aircraft capable of both horizontal and vertical flight including a supporting structure, means for positioning said structure for either horizontal or vertical take-01f including landing gear and a tail support, said landin gear including telescoping casings and oleo units, said casings having pivots at their upper ends movable along tracks disposed generally longitudinally of said craft and said oleo units carrying landing wheels at their free ends, means at the forward end of said tracks for limiting movement of said casings 11 along said tracks, means for latching said casings said f orward position, means for extending said oleo units from said casings to position said craft for vertical take-off, means for first retracting said oleo units and subsequently retracting said casings into'said supporting structure during'which latter movement said pivots move rearwardly along "sjaidt'rac'ks', and means controlled by said oleo units'for releasing said latching means in the fully retracted position of said units;

'4. An aircraft capable of both horizontal and vertical flight including asup'porting structure, means forpositic'mi'r'igsaid craft for either horizontalor vertical take-off and landing, including tail supporting "means'flxed to the structure and landing 'gear' also carried by said structure forward'of said tail supporting means, said landing gear having extensiblefc'asing and strut elements and being retractablewith'in said supporting structure whensam elements are collapsed, a pivoted tail"flap,'h'orizont a1 control surfaces, pilot operated means for 'operating said surfaces, means controlling the extension of said casing elements fromsaid supporting structure and the extension of said strut elements from said casing, 'and'rneans governed by the extending movement of said strut elements for connecting said flap and" said horizontal control surfaces for simultaneous operation by'said operating means.

5. Anaircraft' capable of both horizontal and vertical flight including asupp'orting structure, means forpositioning' s'aid'aircraft on the ground for horizontal onvertical take-oil comprising track means extended"longitudinally of said structure, landing gcarretractible into' saidstructure comprising"'casin gs' and struts extensible therefrom including" relatively stationary and movable element's/said casings having their upper ends slidable'along'saidtrack means, and pilot controlled operating niechanismfor retracting the elements of said struts 'into said casings and said landing ge'ar'into said structure in the order namedi 6. An aircraft capable of both horizontal and vertical flight including" a" supporting structure, retraotible' landing gear "including casings" which are extensible from said' structure and 'struts which are extensible from said "casings in the extended position'of'said casings, latch means for holdingfsaidcasings releasably in extended posi tion,andlatch releasing means controlled by the movableelement or 'said' extensible struts as the latter move intofullyretracted' position in said casings. i

7. Anaircraft capable of both horizontal and vertical flight including a supporting structure, means for positioning the craft 'for'hor'izontal take-01f including landing gear having casings movable from a retracted"positionjwithin said supporting structure" to an extended position, means for positioning'said craftfor vertical takeoff when said casings'are extended-including extensible oleo struts, means responsive to initial extending movement of said oleo' struts, for locking said casings in extended position and for releasing the latter as said struts move to fully retracted position in said'casings.

8. An aircraft capable .of.both horizontaliand vertical. flight including a supporting structure, retractable landing gear including. casings. extensible from said structure and struts whichare extensible from saidcasingsinthe extended position of the latter, means forlocking said struts tofisaid casings and. means responsive. to .move- 12 ments of said casings m5 and out of their fully extendedpositlon for unlocking and locking said Struts. M.

9. An aircraft capable, oi both horizontal and vertical flight inclnding a supportingstructure: landing gear movable between an extendedposi tion and a retractdposition with insjaid structure, said landingg ear mending diagonal cable braces, and canrrneans responsive to movements of said landing gear for slackening said cable braces as said gear 'movesinto retracted position and for tightening the same as said gear is exe l 10. An all-wing aircraft capable of both horizontal and vertical flight including laterally extended horizontaltail;surfaces having operating mechanism, a rearwardlyextended tail flap hav ing operating mechanism, retractable "landing gear including casingfmembers extensible to be: mit horizontal take o'fi and-landing, saidflanding gear also including struts which are extensible from said casing members when the latter are extended to positionsaid craft for vertical land ing and take-off, and"means responsivato ex: tension of said struts'for opratively eonnecting said flap operatingrnechanisrn 'to the operating mechanism for said horizontal surfaces.

11. An all-wing aircraft capable of both horizontal and vertical flight'incl u'd ing a supporting structure, landing gearfixed tolsaid structure, a tailwheel fixed to said structure aft 'of said land} ing gear, said landing gear having extensible struts for positioningsaid'craft for horizontal take-off and landing in 'ith'eir retracted position and for positioning said'craft for vertical takeoif and landing in'th'eir extended position, and a tail flap pivot'ally supported on said structure which is movable to"oounteract a nose-down tendency of "the craft during vertical landing and which forms a fairingfofsaid tailfwheel in normal flight'position'of said tailflap;

12. An allwing aircraft capable'of both horizontal and vertical flight including a; supporting structure, landing gear for'positioning saidcraft at different attitudes fo r horizontal and verticaltake-ofi and landing, aftalil flap pivotally ou e id 'im ie nqrmal is o n substantially longitudinar alignment with said wing during flight and movableinto anangular P i elat ve w e d W wh n th e: is on the ground in position verticalflight, said flap having longitudinal ground engaging mem; berson its bottom surfacei 13. Anaircrait capable of both horizontaland vertical flightincIudinga supporting structure, means for positioning said craftfor either hori-, zontal or vertical take-off including ,landing gear and a tail support, said la nding gear. comprising casing elements andrnovable ,oleo units, said e as; ing elementshavingpivqts at their upper ends ov lon j bwnwa dly nd-f rwa d y p: ing tracks carried by said 7' supporting, structure and said oleo units supporting landing'wheels at their free ends," stop n e ans for limiting the for Ward movement fsaidpivg tsaI ng said tracks, latch means carried by said supporting structure for releasably holding saidpivots in their forward position, latch releasingineans carried by said oleo units for releasing saidlatches as said oleo units move into fully retracted position in said casing elements, means for locking said oleo units in'their retracted position, loclereleasing means carried 1 by' saidoleo units, for controllin said locking means, and meansfor operating. said-lock releasing means to unlock said oleo units as said pivots move toward said stop means.

14. An all-wing aircraft capable of both horizontal and vertical flight including landing gear for positioning said aircraft at different attitudes for horizontal and vertical take-off and landing, a normally free floating trailing edge flap pivoted on said Wing, and means for positively moving said flap above its neutral position as the aircraft approaches the ground in vertical landing.

15. An aircraft capable of both horizontal and vertical flight including a main sustaining surface, extensible and retractible landing gear for positioning said aircraft at different attitudes for horizontal and vertical take-off and landing, a normally free floating trailing edge flap pivoted on said main surface, means for controlling said flap during vertical landing, and means responsive to the extension of said landing gear preparatory to a vertical landing for governing said flap controlling means.

16. In an all-Wing aircraft capable of both horizontal and vertical flight, control surfaces for longitudinal control of said aircraft, a pilot operated member for controlling said surfaces, landin gear for positioning said aircraft at different attitudes for horizontal and vertical take-off and landing, means for projecting said landing gear from a retracted position in said wing into a first projected position in which the aircraft is in position for horizontal take-01f, and means for further projecting said landing gear into a second projected position in which the aircraft is in position for vertical take-off, a tail flap pivotally mounted on said wing and normally free from pilot control, and means controlled by the movement of said landing gear into said second projected position for connecting said flap to said pilot operated member.

CHARLES H. ZIMMERMAN.

REFERENCES CITED The following references are of record in the file of this patent: 

